1. Field of the Invention
The present invention relates to an anchor bolt for use in installing an anchor on a concrete floor surface, a wall surface, a ceiling surface, and so on and to an installing method thereof.
2. Description of Related Art
Anchors to be installed after a concrete frame is matured are classified into adhesive anchors and driving anchors, and both of them include various kinds. FIG. 20 to FIG. 24 show an installing example of the adhesive anchor. In this installation example, an anchor hole 11 is first bored in a concrete frame 9 as shown in FIG. 20. Next, the anchor hole 11 is cleaned with a specialized brush 25 as shown in FIG. 21, and a capsule 15 in which an adhesive is encapsulated is embedded therein as shown in FIG. 22. Then, as shown in FIG. 23, an anchor bolt 18 is screwed in to stir the adhesive while destructing the capsule 15. Thereafter, as shown in FIG. 24, the adhesive is cured to bond the anchor bolt 18 and the concrete frame 9 so that the installation of the anchor bolt 18 is finished. Incidentally, depending on the kind of the adhesive, such a method is also available that an anchor bolt is driven in by a hammer, instead of being screwed in, to mix an adhesive while destructing an adhesive capsule, thereby fixing the anchor bolt.
The biggest problem of such an anchor installation is that a designed installation position of the anchor sometimes encounters the position of a reinforcement arranged in the concrete frame to obstruct the installation of the anchor bolt. Specifically, in order to secure the pull-out strength of the anchor bolt, a predetermined embedded length is required in the concrete frame. However, since the reinforcement is generally arranged in the depth of about 30 mm to about 60 mm from the surface of the concrete frame, the predetermined embedded length of the anchor bolt cannot be secured when the anchor hole encounters this reinforcement (this does not apply to the case when the predetermined embedded length is shorter than a reinforcement covering margin which will be explained next).
This will be explained referring to FIG. 25. Note that this drawing shows a cross section of the concrete frame 9 and the reference numeral 26 in this drawing denotes the surface of the concrete frame 9. A distance F from a reinforcement 12 to the surface 26 of the concrete frame 9 corresponds to the reinforcement covering margin. In FIG. 25, an anchor hole D does not encounter the reinforcement 12 so that a predetermined embedded length L can be secured for the anchor bolt 18. On the other hand, an anchor hole E encounters the reinforcement 12 so that the predetermined embedded length cannot be secured for the anchor bolt 18.
In order to solve this problem, an anchor hole inclining by about 30° from a direction perpendicular to the frame surface 26 is first bored at the anchor bolt installation position and the anchor bolt 18 is driven thereinto, as shown in FIG. 26. Next, as shown in FIG. 27, a force is given to the anchor bolt 18 protruding outside the concrete frame to bend the anchor bolt 18 in the direction perpendicular to the frame surface 26. By this method, the anchor bolt 18 is installed while evading the reinforcement 12.
The above-described installing method of the anchor bolt, however, gives rise to various problems such that the anchor bolt tends to be deviated from the installation position since it is driven in the inclined state, and that the bending work deforms the anchor bolt to lower the strengthen thereof. Therefore, a high degree of skill is required for carrying out the above-described installing method of the anchor bolt.
Incidentally, the anchor bolt having a bolt diameter of M16 or shorter can be manually bent, but it is difficult to bend the anchor bolt having a diameter of M20 or longer manually. So, when the bolt diameter is M20 or longer, the reinforcement encountered by the anchor hole is cut by a diamond cutter to bore an anchor hole to a predetermined depth, thereby installing the anchor bolt. In this case, however, there is such a problem that strength degradation of the concrete frame cannot be avoided since the reinforcement is cut.